Finger blood pressure cuff

Abstract

An aspect of the disclosure pertains to finger blood pressure cuff. The finger blood pressure cuff may include a housing having an opening sized to receive a human finger and an inflatable elastic bladder disposed about an inward-facing surface of the opening. The inflatable elastic bladder may be inflated to pressurize a user's finger and temporarily occlude blood flow in the user's finger. The finger blood pressure cuff may include a pressure sensor for obtaining blood pressure measurements.

What is claimed is: 
     
       1. A device for estimating a user's blood pressure, the device comprising:
 a housing having a hole sized to receive a human finger; 
 a pump; 
 an inflatable elastic bladder disposed about an inward-facing surface of the hole and defining, at least in part, a pressurizable volume in fluidic communication with the pump, wherein the pump is configured to pressurize the pressurizable volume and cause the inflatable elastic bladder to expand towards the center of the hole and contact a user's finger when the user's finger is positioned in the opening of the device and the pump is activated; 
 a pressure sensor in fluidic communication with the pressurizable volume and configured to produce pressure data indicative of a pressure within the pressurizable volume as a function of time; and 
 a controller that is configured with instructions to cause the pump to pre-inflate the inflatable elastic bladder from a first pressure to a second pressure prior to user insertion of their finger into the hole, and configured with instructions to cause the pump to further increase the pressure in the pressurizable volume beyond the second pressure to a third pressure upon determining that the user's finger is inserted into the hole, the third pressure being a pressure at which pulsatile variations are detectable in the pressure data. 
 
     
     
       2. The device of  claim 1 , further comprising:
 a ring-shaped structure disposed within the hole and encircling the inflatable elastic bladder, the ring-shaped structure further defining, at least in part, the pressurizable volume. 
 
     
     
       3. The device of  claim 2 , wherein:
 the ring-shaped structure has a first end and a second end with a cylindrical inner surface spanning between the first end and the second end, 
 the inflatable elastic bladder including a first seal bead and a second seal bead with a membrane structurally interposed between the first seal bead and the second seal bead, 
 the first seal bead being sealed against the first end of the ring-shaped structure and the second seal bead being sealed against the second end of the ring-shaped structure, and 
 the ring-shaped structure including one or more ports that fluidically connect the pressurizable volume with the pump. 
 
     
     
       4. The device of  claim 3 , wherein the one or more ports pass through the ring-shaped structure and are configured to fluidically connect the pressurizable volume with an annular passage encircling the ring-shaped structure and are in fluidic communication with the pump. 
     
     
       5. The device of  claim 1 , wherein the pressurizable volume has a continuous annular shape. 
     
     
       6. The device of  claim 5 , wherein the inflatable elastic bladder has an overall shape that is axially symmetric about a center axis of the hole. 
     
     
       7. The device of  claim 6 , wherein the inflatable elastic bladder includes a plurality of longitudinal ribs that extend along directions parallel to the center axis and that are arranged in a circular array centered on the center axis. 
     
     
       8. The device of  claim 1 , wherein:
 the inflatable elastic bladder includes two or more lobes symmetrically distributed about a center axis of the hole, 
 each lobe including a middle portion bracketed between two end portions, 
 the middle portion of each lobe extending closer to the center axis than the corresponding end portions of that lobe when the pressurizable volume is at zero gauge pressure. 
 
     
     
       9. The device of  claim 8 , wherein the inflatable elastic bladder has three lobes symmetrically distributed about the center axis. 
     
     
       10. The device of  claim 8 , wherein the controller is configured with instructions to:
 control the pump to further increase the pressure in the pressurizable volume to a fourth pressure at which pulsatile variations in the pressure data indicative of the pressure within the pressurizable volume decrease to a first predetermined level, 
 control the pump to deflate the pressure in the pressurizable volume, and 
 control the pump to re-inflate or maintain the pressure in the pressurizable volume at a target pressure, wherein the target pressure is less than the fourth pressure, wherein the pressure is held at the target pressure for a duration between about 3 seconds and about 10 seconds. 
 
     
     
       11. The device of  claim 8 , wherein the inflatable elastic bladder has a helical twist about the center axis of the hole. 
     
     
       12. The device of  claim 1 , wherein the inflatable elastic bladder is made of silicone or other elastomer having a Young's modulus selected from the group consisting of: between about 0.001 GPa to about 0.1 GPa and between about 0.003 GPa to about 0.05 GPa. 
     
     
       13. The device of  claim 12 , wherein an external surface of the inflatable elastic bladder is oxidized through exposure to ultraviolet radiation to reduce a tackiness of the inflatable elastic bladder. 
     
     
       14. The device of  claim 1 , wherein:
 the inflatable elastic bladder includes a membrane section that transitions to a bellows section at opposing ends, 
 each bellows section extending back towards the other bellows section from where that bellows section transitioned to the membrane section, 
 each bellows section terminating in a seal bead that encircles the membrane section. 
 
     
     
       15. The device of  claim 14 , wherein:
 the membrane section has a first length along a center axis of the hole, 
 the bellows sections both have a second length along the center axis of the hole, and 
 the second lengths are each between 15% and 35% of the first length. 
 
     
     
       16. The device of  claim 14 , wherein: the membrane section and the bellows sections have nominal thicknesses selected from the group consisting of: between about 0.1 mm and about 0.75 mm and between about 0.25 mm and about 0.5 mm. 
     
     
       17. The device of  claim 1 , wherein the inflatable elastic bladder has a length along a center axis of the hole that is selected from the group consisting of: between about 0.5 inches and about 1.5 inches and between about 0.75 inches and 1.25 inches. 
     
     
       18. The device of  claim 1 , further comprising one or more proximity sensors. 
     
     
       19. The device of  claim 1 , wherein the inflatable elastic bladder is configured to be inflated to a volume between about 3 cubic centimeters and about 10 cubic centimeters. 
     
     
       20. The device of  claim 1 , wherein the housing includes a circumferential lip that:
 extends around the hole, 
 forms an aperture smaller than the hole when viewed along a center axis of the hole, and 
 obscures a portion of the inflatable elastic bladder from view when viewed along the center axis with the device oriented such that the inflatable elastic bladder is behind the circumferential lip.